Tool for boring polygonal holes.



APPLICATION EILED MAY 2|, 19H- Patented June 18, 1918.

JAMES J. B. G-MLXMORE, OI? DETROIT, MICHEEGAIN.

TOOL EOE BORING: POLYGONAL HOLES.

flpecification of Letters Iatent.

To all whom it may concern:

Be it known that 1, JAMES J. S. GALLP MORE, a subject of the King of Great Brit ain, residing at Detroit, in the county of Wayne and State of Michigan, have invent ed certain new and useful linprovei'ncids in Tools for Boring Polygonal l loles, of which the following is e speeifiation, reference pose which may be cheaply manufactured and is adopted for use in connection with any machine or device adapted for holding or operating" boring tools, and the invention consists in the form and construction of such a tool and in the matters hereinafter more fully set forth, reference beinghad to the accompanying drawing in which Figure 1, is u side elevation of a tool illustrative of the invention with portion of the same broken away to better show the construction, and also showing the same in operative position and held by suitable rotating and guiding means;

Fig.2 is a perspective View of the tool detached; I

Fig. 3 is a transverse section of the tool on a plane adjacent to and above the work, with the work in plan view;

Fig. 4 is an end elevation of the tool, and showing in plan view a form of guide plate therefor;

Fig. 5 is a view similar to Fig. 3, illustrating a modified form of tool for boring octagonal holes;

Fig. 8 is a transverse section through that portion thereof which is adapted to engage the former plate;

Fig. 7 is a view similar to Fig. 5 showing a modified form of tool for boring decugonal holes; and I Fig. 8 is a sectional view of the same, similar to Fig. 6.

For the purposes of illustration, a particular form of tool is shown, but obviously changes may be made there-in within the scope of the appended claims, without cle- Patented June Tilt, 1918.

Application filed May 21. 1917. Serial in. 169,863.

parting from the spirit of the invention and l do'not therefore wish to limit myself to the particular construction shown.

In the drawing, 1 denotes the spindle of a suitable drill press or other n'mchiuc adapt ed to hold and drive a boring; tool, i! u chuck for grouping the shank oi a tool, und. 3 a suitublo coupling which will porn'ail; oi a lateral movement oi the chuck and tool relative to the driving spindle during rotation. 4 a suitable guide or former plate which isrigidly supported in any suitable manner with an opening 5 therein in axial alinement with the driving spindle, said opening being or the size and form which it is desired to bore in the work 6 and through which opening 5 the tool T extends and is guided thereby. The tool is revolved in contact with the walls of this opening in the former plate but it will be understood that this plate may be dispensed with by first forming a hole in the Work oi the same form and size as the hole to be bored and of sullicient depth so that the walls thereof will form a. guide for the tool.

The tool comprises a body portion and a reduced end portion, forn'iiug u shank 8 by means of which it may be secured in a chuck or other holding device and rotated. The tool is so shaped that when rotated within a suitably shaped guide opening of polygonal form having diametrically disposed angles, and opposed parallel fiat sides or walls, the resistance o'll'cred by the materiul being bored to the movement of the cutting edge 9 formed on the lower end of the tool, will forcc'said tool toward one side of the guide opening and cause it to follow the contour thereof throughout rotation, and to cause the tool to out true to the straight walls of the former opening or guide and into the angles formed by the juncture of said wells, it is inuiierutive that the tool have a minimum of lateral play in the former or hole in the direction of the length of the cutting edge, in all positions of its turning movement, that is, the dimensions of the tool should be such that the side thereof at which the cutting edge is located will be held in contact with the walls of the guide in all positionsof the tool, by the contact of the opposite side of the tool with the guide walls. 0 prevent such lateral movement, the tool should have three points of contact with the guide or former, one substentielly in the plane of the outer end of the cutting edge of the tool or at the angle the polygon intersects one side thereof, tangent with the opposite parallel side and noting Where this are intersects the adjacent sides of the polygon. This will give the maximum length of the base line of the triangle, or a triangular shaped figure of maximum dimensions which will turn with in the polygonal opening, and by giving said base line of the triangle a curve corresponding to, said arc, the tool, in turning in contact with the walls of the polygonal opening, will rock thereon and cause the point or apex of the triangle to describe a straight line corresponding to a straight side or flat of the polygon.

The longitudinal axis of the tool will describe a path about the center of the polygonal hole being bored and therefore in order that the material may all be cut away, at the bottom of the hole, the cutting edge 9 of the tool is formed on the lower end thereof. along a line extending approximately from the point or angle 10 to or be yond the said axis of the tool, the body of the tool being cut away at'its forward or advance side for a distance upwardly from said cutting edge to give clearance for the chips out from the work in boring.

For the purpose of strength, the rear side of the tool opposite that which is cut away to form the cutting edge, may be given an angular form, as at 14, corresponding to the. ad acent faces of'the opening, that is the space between one side of the necessary triangle shaped figure, the sides of which are described by the dotted line 13, and the ad- 'jacent walls of the hole being bored when the tool is in the position shown in Fig. 4c,

- may be filled in, and in a like manner, when the former plate 4 is employed, that portion of the body which rotates within the opening of the plate may be formed, for the purposes of strength and symmetry, with an angularportion at each side of the triangular portion as shown at 15 in Fig, 4:, identical in shape with that of the portion 14, making, in cross section, a five sided figure.

In Figs, 5 and 6, a tool for boring octagonal holes is illustrated, but the foregoing descriptin of the construction and operation of the tool for boring hexagonal holes shown in Figs. 3 and l will apply as well to the tool illustrated in these figures, or to an tool for boring even sided polygonal ho es, such as is further illustrated in Figs. '2" and 8, where a tool for boring decagonal holes is shown.

Having thus fully described my invention what I claim is:

l. A tool for boring polygonal holes including a guide having a polygonal opening, a part adapted'to be rotated Within said polygonal opening and to simultaneously contact the Walls thereof at three points, one o:t said points of contact being equidistant from the other two and at a distance from each substantially equal to the shortest diameter of said poly onal opening, and said other two points ing a greater distance apart than the distance between. adjacent angles of the polygonal opening, said rotatable edge on'its lower end.

2. A. tool for boring polygonal holes in cluding a guide having a polygonal opening, a part adapted to contact the walls part having a cutting Mid sides of which figure are substantially egnal in length to the shortest diameter or said polygonal opening, and the base line of which triangular figure is greater in length than any one side of said pol gonal opening, said part being provided with a cutting portion at its lower end.

Zitit as. tool for boring polygonal holes in eluding a guide having a polygonal opening, a part adapted to contact the walls of said polygonal opening at points defining the three angles of a triangular figure with a side of said part forming the base line of said figure and defining the arc of a circle whose center is at the apex of said trianular figure, and the radius of which circle is substantially equal to the shortest diameter of said polygonal opening.

5. A tool for boring polygonal holes in cluding a guide having a polygonal opening a art adapted to contact the walls of said, po ygonal opening at points defining the three angles of a triangular figure, the base line of which is the arc of a circle whose one wall of said dpolygonal opening, said part'having an en cutting portion.

6. A tool for boring polygonal holes including a guide having a polygonal opening, a part adapted to contact the walls of said polygonal opening at points defining the three angles of a triangular figure, said tool having a cutting edge formed on its lower end extending substantially radially of said end from one of said points of contact to a point beyond the longitudinal axis of the tool whereby said cutting edge will cut away the material at the center of the hole to be bored.

7. A tool for boring polygonal holes ineluding a guide having a polygonal opening, a part adapted to contact the walls of said polygonal opening at points defining the three angles of a triangular figure, said tool being cut away at one side at its lower 20 end inwardly from one of said contact points substantially toward the axis of rotation of said part, to provide clearance and a cutting edge.

In testimony whereof I aifix my signature 25 in the presence of two witnesses.

JAMES J. S. GALLIMORE. Witnesses:

ANNA M. Dona, G. E. MoGRaNN, 

